Bumper system with face-mounted energy absorber

ABSTRACT

A bumper includes a beam and an energy absorber supported thereon. The energy absorber includes horizontal walls, each having a front portion, a rear portion, and an interconnecting mid-portion that offsets and misaligns the front and rear portions. Upon impact, the front and rear portions collapse with the offset mid portion wrapping back upon itself with a predictable energy-absorbing collapse. The energy absorber further includes flanges and friction pads that frictionally engage the top and bottom of the beam to temporarily retain the energy absorber to the beam. In one embodiment, the front beam wall includes at least one aperture, and the energy absorber includes a tubular column extending from its front wall through the aperture in the front beam wall to the rear beam wall. By this arrangement, the front wall of the energy absorber receives support from the front beam wall via the structural column.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of application Ser.No. 10/061,670, filed Feb. 1, 2002, entitled BUMPER SYSTEM WITHFACE-MOUNTED ENERGY ABSORBER, which in turn claims benefit under 35U.S.C. 119(e) of a provisional application Serial No. 60/283,969, filedApr. 16, 2001, entitled BUMPER SYSTEM WITH FACE-MOUNTED ENERGY ABSORBER.This application is further a continuation-in-part of application Ser.No. 09/967,196, filed Sep. 28, 2001, entitled BUMPER SYSTEM WITHFACE-ABUTTING ENERGY ABSORBER, which in turn claims benefit ofprovisional application Serial No. 60/284,058, filed Apr. 16, 2001,entitled BUMPER SYSTEM WITH FACE-ABUTTING ENERGY ABSORBER under 35 USC§119.

BACKGROUND OF THE PRESENT INVENTION

[0002] The present invention relates to automotive bumper systems havingbeams and energy absorbers located on faces of the beams.

[0003] Many vehicle designs use energy absorbers positioned on a face orfront surface of a steel bumper beam to improve energy absorption of abumper system. The energy absorbers provide an initial level of energyabsorption for low impact, including reducing damage during low impact,and also provide a supplemental level of energy absorption during highimpact (i.e. before and at the time that the beam and vehicle begin toabsorb substantial amounts of energy). Usually, the energy absorbers arefastened to the bumper beam with fasteners that assure accuratepositioning of the energy absorber on the beam. The reasoning includesaccurately positioning the energy absorber on the bumper beam to assureconsistent performance, as well as to assure accurate positioning foraesthetics and assembly (e.g. to assure a good fit of the front-endfascia over the energy absorber and beam during assembly).

[0004] However, improvements are desired in terms of temporary andpermanent attachment, and for improved and more reliable energyabsorption. Typically, attachment of the energy absorber to bumper beamsrequires a plurality of mechanical fasteners. This is disadvantageoussince mechanical fasteners require manual labor to install, which canadd undesirably to cost. Also, the mechanical fasteners can result inlocalized and non-uniform stress distribution during impact, resultingin inconsistent collapse of the bumper system and poor energy absorptionon impact. Further, fixing the energy absorber to the beams results inan inability of the energy absorber to shift and adjust tonon-perpendicular and uneven loads transmitted from the impactingbodies. At the same time, depending on the bumper system, sometimesshifting of an energy absorber is not good since it can result inunpredictable, premature and non-uniform collapse, resulting in poor orinconsistent energy absorption by the bumper system.

[0005] Improvement is also desired for corner impact structure on bumpersystems. Many existing bumper systems require that a front surface of anend of a bumper beam be shaped at an increased angle relative to thefront of rest of the bumper beam to match an aerodynamic curvature ofthe vehicle at its front fender. One way to achieve this is by mitercutting an end of the bumper beam at an angle, and thereafter welding aplate onto the angled end to form a compound-angled flat front surfacefor supporting an energy absorber such as a foam cushion. Another way isto deform or crush an end of the bumper beam to form an angled frontsurface. Yet another way is to weld a bracket onto an end of the bumperbeam, with the bracket extending longitudinally beyond the bumper beamto form the desired shape. However, all of these alternatives havedrawbacks. For example, they each require a secondary operation, resultin increased dimensional variation, and require significant investmentin capital equipment. Further, they can lead to increased scrap, asubstantial increase in manpower and manufacturing time, and substantialincrease in inventories and work in process.

[0006] For all of the above reasons, there is a desire for bumpersystems that yield a better, more consistent, more reliable, and greaterimpact energy absorption, both for low and high impact events, and alsofor square and skewed impact directions. Also, there is a desire forimprovements facilitating assembly of an energy absorber to a beam, withlower cost and fewer parts, and with less labor. Still further, there isa desire for energy absorber designs that allows adjustment and tuningfor optimal front end and corner impact strengths, even late in thebumper development program, and yet that do not require expensive orcomplex molding techniques or assembly techniques nor secondary mitercutting or crush forming bumper end sections. Still further, there is adesire for energy absorber designs that are adaptable for use with manydifferent bumper beam cross-sectional shapes and sizes. Also, energyabsorber designs are desired that are flexible and usable on non-linearbumper beams having different curvatures and longitudinal sweeps, andhaving different cross sections.

SUMMARY OF THE PRESENT INVENTION

[0007] In one aspect of the present invention, a bumper system for apassenger vehicle includes a beam having a face and adapted forattachment to a vehicle frame, and an energy absorber supported againstthe face of the beam. The energy absorber includeslongitudinally-extending top and bottom horizontal walls. At least partof one of the top and bottom horizontal walls includes a front portion,a rear portion extending parallel the front portion, and an offsetmid-portion that interconnects the front and rear portions but thatoffsets and misaligns the front and rear portions. By this arrangement,upon a frontal impact, the front and rear portions telescopinglycollapse with the offset mid portion wrapping back upon itself with apredictable energy-absorbing collapse.

[0008] In another aspect of the present invention, a bumper system for apassenger vehicle includes a beam having a face and top and bottom beamwalls and being adapted for attachment to a vehicle frame, and an energyabsorber supported against the face of the beam. The energy absorberincludes a plurality of horizontally-and-longitudinally-extending topand bottom walls that generally align with the top and bottom beamwalls, and further includes flanges that overlap onto the top and bottombeam walls and that include at least a pair of fingertip-like frictionpads that frictionally engage the top and bottom beam walls totemporarily retain the energy absorber to the beam.

[0009] In yet another aspect of the present invention, a bumper systemfor a passenger includes a beam having front and rear beam walls, andthat is adapted for attachment to a vehicle frame. The front beam wallincludes at least one aperture in the front beam wall, with the rearbeam wall including a support area located behind and spaced from the atleast one aperture. An energy absorber is supported against the frontbeam wall, and includes a plurality of horizontally-extendinglongitudinally-extending top and bottom walls and further includes frontand rear walls. The energy absorber walls includes at least onestructural column extending from the front wall through the rear walland through the at least one aperture in the front beam wall to alocation near the support area on the rear beam wall. By thisarrangement, the front wall of the energy absorber receives support fromthe front beam wall via the structural column.

[0010] These and other aspects, objects, and features of the presentinvention will be understood and appreciated by those skilled in the artupon studying the following specification, claims, and appendeddrawings.

BRIEF DESCRIPTION OF DRAWINGS

[0011]FIG. 1 is a perspective view of a bumper system of the presentinvention, including a bumper tubular beam and an energy absorber on aface of the bumper beam;

[0012]FIG. 2 is a rear perspective view of the energy absorber of FIG.1;

[0013]FIG. 3 is an enlargement of the circled area III in FIG. 1;

[0014] FIGS. 4-6 are cross-sectional views of the bumper system of FIG.1, FIG. 4 being before impact, FIG. 4A being similar to FIG. 4 butshowing the structure needed to avoid die lock during molding, FIG. 5being at a time of low impact, and FIG. 6 being at a time of highimpact, respectively;

[0015] FIGS. 7-7B are fragmentary top views of a prior art bumpersystem, FIG. 7 showing a bumper beam including an angled miter cut (indashed lines), FIG. 7A showing a plate welded onto the angled end of thebumper beam, and FIG. 7B showing a foam energy absorber on the bumperbeam;

[0016]FIG. 8 is a perspective view of another bumper system including abumper beam and an energy absorber with rearward projections extendingthrough holes in a front surface of the bumper beam;

[0017]FIG. 9 is a cross sectional view taken along line IX-IX in FIG. 8;

[0018]FIG. 10 is a front perspective view of a bumper system includingthe bumper beam and the energy absorber;

[0019]FIG. 11 is a rear perspective view of the energy absorber of FIG.10; and

[0020] FIGS. 12-14 are front, top and bottom views of the energyabsorber of FIG. 11, and FIG. 15 is an enlarged view of the right halfof FIG. 12;

[0021]FIG. 12A is a front view like FIG. 12, but with a front face ofthe energy absorber shaded to better show the “box-shaped” areas on theenergy absorber;

[0022] FIGS. 16-20, 22, 24, and 25 are cross sections along the linesXVI-XVI through XX-XX, XXII-XXII, XXIV-XXIV, and XXV-XXV in FIG. 15; and

[0023]FIGS. 21 and 23 are views similar to FIGS. 20 and 22, but afterbeing deformed after impact.

[0024]FIGS. 26 and 27 are fragmentary perspective views of a bumpersystem of the present invention, including a bumper beam and an energyabsorber;

[0025] FIGS. 28-31 are cross-sectional views of the energy absorbertaken along the lines III-III, IV-IV, V-V, and VI-VI in FIG. 27; and

[0026]FIGS. 32 and 33 are front and rear perspective views of the energyabsorber shown in FIG. 2, and FIG. 33A is a fragmentary perspective viewof a portion of FIG. 33.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0027] The present invention is described as utilizing a B-shapeddouble-tube bumper beam that is rollformed and swept. The presentB-shaped bumper beam is sufficiently described herein for a personskilled in the art to understand and practice the present invention, butit is noted that the process and method of making the illustratedB-shaped bumper beam is described in greater detail in Sturrus patentU.S. Pat. No. 5,454,504, if the reader desires such information. It isspecifically contemplated that the present invention could be used incombination with a bumper beam having a shallower channel instead of thedeep channel illustrated. For example, it is contemplated that thepresent invention could be made to work on a D-shaped bumper where thebumper beam had a channel extending significantly into a front face ofthe bumper beam but where the channel does not extend completely to arear wall of the bumper beam. On the merits, the teachings of U.S. Pat.No. 5,454,504 are incorporated herein in its entirety for the purpose ofproviding a complete disclosure of the entire bumper system.

[0028] Bumper system 20 (FIG. 1) includes a bumper beam 21 attached to avehicle, and an energy absorber 22 attached to a face of the bumper beam21. The illustrated bumper beam 21 is attached by brackets 20A. Crushtowers can also be used to mount the bumper beam. The illustrated beamis rollformed and swept (see Sturrus patent U.S. Pat. No. 5,454,504) andhas a continuous B-shaped double-tubular cross section (FIG. 3). Thedouble tubes are spaced vertically apart and include top and bottommid-walls 23 and 24 defining a longitudinally-extending channel 25 alongits front surface. A polymeric energy absorber 22 has a length withmultiple top and bottom box-shaped sections 27 and 27 (not all being thesame size or length) that abut the front surface 26 of the bumper beam21. The energy absorber 22 further includes a plurality ofrearwardly-extending nose sections 28 that extend into the channel 25.The nose sections 28 are trapezoidally-shaped to fit mateably into thechannel 25, and extend about 50% to 60% of the way to a bottom of thechannel 25. Where desired, the nose sections 28 include detents or areshaped to provide sufficient frictional engagement to temporarily retainthe energy absorber 22 on the bumper beam 21. The illustrated nosesections 28 include collapse-controlling kick walls 30 and 31 that liealong and abut the top and bottom mid-walls 23 and 24 of the bumper beam21. The kick walls 30 and 31 are non-parallel and are connected to thebox-shaped sections 27 and 27′ so that, upon impact by an object againstthe bumper system, the kick walls 30 and 31 bend in a predictable andpreplanned manner and press into the top and bottom mid-walls 23 and 24.During high impact (see FIGS. 3 and 4), the kick walls 30 and 31 presswith increasing force, resulting in a more consistent and controlledflexure and collapse of the box-shaped sections 27 of the polymericenergy absorber 22 and of the tube sections of the metal bumper beam 21as a system. The nose sections 28 are trapped within the channel 25,which eliminates the problem of the energy absorber sliding verticallyoff a face of the bumper beam (which is a problem in some bumper systemsusing an energy absorber mounted to a face of a bumper beam).

[0029] The B-shaped section of the bumper beam 21 includes, in additionto top and bottom mid-walls 23 and 24, a top wall 34, a front upper wall35, a bottom wall 36, a front lower wall 37, a rearmost rear wall 38 anda channel-forming rear wall 39. The top tube of the bumper beam 21 isformed by the walls 23, 34, 35, and 38. The bottom tube of the bumperbeam 21 is formed by the walls 24, 36, 37, and 38. The top and bottomtubes are interconnected by rear walls 38 and 39. Each of these walls23-24 and 34-39 can be flat or non-flat. For example, in some bumpersystems (such as the illustrated walls 23-24), it has been found to bebeneficial to make the horizontal walls 23, 24, 34, and 36 slightly bentor curved, both for purposes of providing a bumper beam that is lesslikely to prematurely kink and more likely to reliably and consistentlybend, but also for the purpose of ease of manufacture of the bumperbeam. As illustrated, the mid-walls 23 and 24 include front portionsthat are angled to created a tapered throat into which the nose sections28 of the energy absorber 22 tend to move upon impact. The mid-walls 23and 24 also include relatively flat rear portions that are generallyparallel. It is noted that, upon a low force impact, the energy absorber22 may move partially into this throat (see FIGS. 4-6) and, ifsufficient energy is absorbed during the low energy impact, may returnto an original shape without substantial deformation or damage to thevehicle or the bumper system.

[0030] The energy absorber 22 (FIG. 3) is a molded component of non-foampolymer, such as a blend of PC/ABS/PBT. For example, it is contemplatedthat General Electric's XENOY polymer will work for this purpose. Asnoted above, the energy absorber 22 includes top and bottom box-shapedsections 27 and 27 that abut a front of the front walls 35 and 37. Thetop box-shaped sections 27 engaging the top front wall 35 can be shapedslightly different than the bottom box-shaped sections 27′ that engagethe bottom front wall 37, if desired, but in the presently disclosedpreferred embodiment, they are similar in size and shape to betterassure a uniform and balanced collapse upon impact. The top box-shapedsections 27 include a front wall 41, open rear area 42, top wall 43 andbottom wall 44, as well as end walls 45 and 46 that tie the walls 41,43-44 together. The bottom box-shaped sections 27′ include similar walls41 ′-46′. Walls 46A, 46B, and 46C extend between and interconnect thetop and bottom box-shaped sections 27 and 27′. It is noted that the topand bottom walls 43, 44, 43′, and 44′, when viewed from a position infront of the bumper system, can be wavy or otherwise nonlinear andnon-flat in shape. This provides the top and bottom walls 43, 44, 43′,and 44 with increased strength for resisting buckling, and also helpseliminate distortions such as snaking that occur when molding a longpart. It is also noted that the surfaces defined by the front walls andrear areas 41, 42, 41′, and 42′ (and potentially the top and bottomwalls 43, 44, 43′ and 44′) are discontinuous and further includeapertures to prevent die lock when molding. (i.e. They include aperturesto allow mold tooling to pass through the plane of one wall to formanother wall.) In a preferred form, the apertures are sufficient in sizeso that the molding dies do not require slides or pulls. In other words,the energy absorber 22 can be made by using hard male and female molds,neither of which require secondary movable die components for creatingblind surfaces.

[0031] The nose sections 28 (FIG. 4) include kick walls 30 and 31, andfurther include a connector wall 48 that interconnects the leading(rear-most) ends of the kick walls 30 and 31. The connector wall 48 islocated halfway into channel 25 so that it acts as a guide during impactto guide the leading ends of the kick walls 30 and 31 into the channel25. Specifically, the connector wall 48 is positioned about 30% to 80%of the way into the channel 25, or more particularly about 50% to 60%into the channel 25. This results in the energy absorber 22 being ableto absorb significant energy, such as may be incurred in a low energyimpact. Specifically, in a low energy impact (FIG. 4), the energyabsorber 22 absorbs a majority of the energy of the impact energy, andthe energy absorber 22 and the bumper beam 21 do not permanently deform.In an intermediate energy impact (FIG. 5), the energy absorber 22deforms substantially, potentially taking on a permanent deformation.However, the bumper beam 21 deflects and absorbs energy, but themid-walls 23 and 24 only temporarily flex and do not permanently deform.In a high-energy impact (see FIG. 6), the kick walls 30 and 31 cause themid-walls 23 and 24 to buckle as they approach a maximum amount ofdeflection. Both the energy absorber 22 and the bumper beam 21permanently deform. The point of buckling is designed into the bumpersystem 20 to cause a two-step collapse (FIGS. 5-6) so that a maximumamount of energy is absorbed without damaging the vehicle, whileconsidering all relevant factors such as preferred de-accelerations,occupant safety, government standards, and the like.

[0032] The top kick wall 30 (FIG. 4)includes a root region 50 thatconnects to the bottom wall 44 of the top box section 27, and the bottomkick wall 31 includes a root region 51 that connects to the top wall 43′of the bottom box section 27′. This direct connection allows the nosesection 28 to react quickly and directly to an impact, because theimpact energy is transferred directly through the bottom wall 44 of thebox section 27 to the kick wall 30, and because the impact energy istransferred directly through the top wall 43′ of the bottom box section27′ to the kick wall 31. Due to walls 42, the natural flow of materialat 50 and 51 during impact cause the material to move into walls 30 and31 along directions A and B, respectively (see FIG. 5).

[0033] A top flange 53 (FIG. 4) extends rearwardly from the top boxsection 27, and a bottom flange 54 extends rearwardly from the bottombox section 27′. The flanges 53 and 54 engage top and bottom surfaces onthe bumper beam 21. Optionally, the flanges 53 and 54 can includeattachment tabs or hooks for engaging apertures or features in thebumper beam 21 for retaining (temporarily or permanently) to the bumperbeam 21. The illustrated flanges 53 and 54 include fingertip-like pads53′ and 54′ that frictionally engage top and bottom surfaces of thebumper beam 21. These frictional flanges 53 and 54 are advantageous inthat all (or most) fasteners can be eliminated. It is also noted thathooks may extend through holes in the faces 35 and 37 of the bumper beam21 and retain the energy absorber 22 on the beam 21.

[0034] It is noted that the present arrangement (see FIGS. 3 and 4-6)“reverses” the B-shaped cross section of the bumper beam 21 relative tothe vehicle that it is attached to, which creates a usable energyabsorbing crush space within the channel of the bumper beam 21.Previously, B-shaped bumper beams were typically used with the flat sideof the B shape facing forwardly and supporting the energy absorber.However, with the flat side of the B shape facing forwardly, the knownenergy absorbers can only collapse against the flat side. Thus, energyabsorption is more limited than in the present design. Specifically, thepresent arrangement of FIGS. 4-6 provides for a more controlled andpredictable two-stage energy absorption upon impact, because the energyabsorber kick walls 30 and 31 stabilize the walls 23 and 24 of thebumper beam 21 during initial impact. Further, the arrangement causesthe nose section 28 to slide into the channel of the bumper beam 21,providing an intermediate step of energy absorption, which helps inreading sensor outputs for sensing impacts, such as are used for air bagdeployment. Still further, it is believed to be novel to utilize wallstructure in an energy absorber to “kick” out and cause predictablecollapse of a steel bumper beam (see FIG. 6), as in the presentinvention described above.

[0035] It is contemplated that corner sections can be molded onto endsof the energy absorber 22 or integrally formed as part of the energyabsorber. Advantageously, the corner sections can be specificallydesigned to satisfy a variety of functional and aesthetic conditions.For example, the corner sections can be square-shaped and can be moldedwith any amount of wall thickness and ribs desired, such thatsubstantially increased amount of corner impact loading can besuccessfully dissipated by the corner section. Alternatively, adifferent polymeric material can be molded onto ends of the energyabsorber to create the corner section, such as a glass reinforcedstiffer polymeric material.

[0036] FIGS. 8-9 show a bumper system 200 including a D-shapedsingle-tube bumper beam 201 supported on mounting towers 202, and anenergy absorber 203 that functions similar to the bumper beam 20 andenergy absorber 21 discussed above. The bumper beam 201 includes twospaced apertures 204 in its front surface 205, and the energy absorber203 includes rearwardly projecting nose sections 206 that projectthrough the apertures 204 and that extend to the rear wall 207 of thebumper beam 201. The illustrated nose sections 206 abut the rear wall207, but it is noted that they can terminate short of the rear wall 207to provide a stepped crush stroke that provides different levels ofenergy absorption at different impact stroke depths. It is contemplatedthat more or less apertures 204 and nose sections 206 can be used.During a vehicle impact, the nose sections 206 provide an initial levelof impact strength and energy absorption. As the impact strokeincreases, the nose sections 206 buckle outwardly, and engage top andbottom walls of the bumper beam 201. An advantage of the bumper system200 is that it provides good localized control and a consistent andrepeatable energy absorption over energy absorption during impact.

[0037] Prior art (FIGS. 7-7B) includes a B-shaped bumper beam 221, mitercut at an angle along a line 222, with a flat plate 223 welded onto thecut end to provide an extended flat front surface having an increasedangle at the miter cut end. A foam energy absorber 224 is positionedagainst the flat front surface of the bumper beam 221, and extends ontothe flat plate 223. The arrangement below eliminates the need to mitercut ends of a bumper beam, which is advantageous because miter cuttingis an expensive secondary operation that takes time, money, equipment,and results in increased inventories. The invention described beloweliminates the miter cutting and secondary operations needed in thebumper system 221/222.

MODIFICATION

[0038] Bumper system 100 (FIG. 10) includes a B-shaped bumper beam 101and an energy absorber 102 attached to the beam's “flat” front face. Theenergy absorber 102 incorporates box-shaped sections similar to theconcept of the energy absorber 22 previously described, but does so in amanner permitting the energy absorber 102 to be used on the “flat” sideof the B-shaped bumper beam 101 (i.e. the side of the B-shaped bumperbeam 101 that does not have a channel formed in it (see FIGS. 18 and20)), as described below. Also, the energy absorber 102 can be used on aD-shaped or single tube bumper beam.

[0039] The bumper beam 101 has the same shape and walls as the bumperbeam 21, except that the bumper beam 101 has an opposite longitudinalcurvature for matching an aerodynamically-shaped curved front of avehicle. In the beam 101, the longitudinal curvature places the “flat”surface 103 (FIG. 20) on a front side of the bumper beam 101, and thetwo tube sections 104 and 105 and the channel 106 therebetween on a rearside of the beam 101. Two mounting brackets or plates 107 and 108 (FIG.10) are attached to the tube sections 104 and 105. The mounting plates107 and 108 each have a flat plate section 109 that engages and iswelded to a back side of the tube sections 104 and 105. A section 110(FIG. 13) extends from the mounting plates 107 and 108 at a locationabout 1 inch to 1-{fraction (1/2)} inches from an end of the tubesections 104 and 105. The sections 110 each include an outer leg 112that extends rearward of the plate section 109, generally at a corner ofthe vehicle. It is contemplated that the mounting plates 107 and 108 canhave a forward loop 111 that partially covers an end surface of theenergy absorber if desired (see FIG. 25). Coplanar flanges 113 and 114(FIG. 13) extend from the rear/outer ends of the brackets 107 and 108.It is noted that other mounting systems can be used for vehicleattachment on the present bumper system if desired.

[0040] The energy absorber 102 is symmetrical about a centerline 115(FIG. 12A), with each half of the energy absorber 102 including fourbox-shaped sections 117-120, each being interconnected bylongitudinally-extending walls, as described below. The box-shapedsection 117 (FIG. 12A) is adjacent the centerline 115 and includes afront face wall 121, a top wall 122, a bottom wall 123, an inboardsidewall 124 and an outboard sidewall 125. A rear of the box-shapedsection 117 is open and the walls 122-125 have draft angles, so that thebox-shaped section 117 can be formed on molding dies that do not requiredie pulls or other moving parts for forming blind surfaces. Two large“crush-initiator” apertures 126 (FIG. 15) are formed in the inboardsidewall 124 to weaken the box-shaped section 117, to provide for anoptimal crush stroke upon impact against the bumper system 100 andspecifically to provide for optimal energy absorption during the crushstoke. The illustrated apertures 126 are each about {fraction (1/3)} ofa total height of the inboard sidewall 124 (see FIG. 18), are located ata top third and a bottom third of the sidewall 124, and extend to a fulldepth of the sidewall 124. Different shapes of apertures can be used.The illustrated apertures 126 are not rectangular, but instead have atleast one curved edge 126′, which is designed to initiate a controlledcrush during an impact for optimal energy absorption during impact, andwhich is also designed to facilitate molding. A strip of materialbetween the apertures 126 and also the strips of material above andbelow the apertures 126 form the structure of sidewall 124. Apertures127 (FIG. 15) are also formed on the front face wall 121 as desired,such as to reduce mass, improve tooling, and provide clearances andattachments to fascia. The outboard sidewall 125 has a C-shaped profile(when viewed in a car-mounted position), and has a vertical centerportion 128 that is located closer to the centerline 115 than the upperand lower portions. A top angled portion 129 of the front face wall 121slopes rearwardly from a remainder of the vertical front face wall 121,which is more vertically oriented, but not perfectly vertical.

[0041] The box-shaped section 118 (FIG. 12A) is adjacent the box-shapedsection 117 and includes a front face wall 131, a top wall 132, a bottomwall 133, an inboard sidewall 134 and an outboard sidewall 135. Thebox-shaped section 118 is about double a width of the box-shaped section117 (in a longitudinal direction), and the inboard sidewall 135 isC-shaped to a longitudinal width about double the dimension of theC-shape of the outboard sidewall 124 of the center box-shaped section117. Also, a top angled portion 139 of the front face wall 131 has avertical dimension that is slightly less than the top angled portion 129of the center box-shaped section 117, so that the combined front face ofthe energy absorber matches a shape of the fascia panel placed on it.The outboard sidewall 135 (FIG. 17) has three apertures 136 that aresimilar to the apertures 126 found in the sidewall 124 described above,with the exception that one of the apertures 136 is formed in each thirdof the outboard sidewall 135.

[0042] The box-shaped section 119 (FIG. 12A) is adjacent the box-shapedsection 118 and includes a front face wall 141, a top wall 142, a bottomwall 143, an inboard sidewall 144 and an outboard sidewall 145. Thebox-shaped section 119 is about {fraction (2/3)} of a width of thebox-shaped section 118 (in a longitudinal direction). The inboard andoutboard sidewalls 144 and 145 are relatively flat (i.e. are notC-shaped). Also, a top angled portion 149 of the front face wall 141 hasa vertical dimension that is slightly less than the top angled portion139 of the box-shaped section 118, so that the combined front face ofthe energy absorber matches a shape of the fascia panel placed on it.The inboard and outboard sidewalls 144 and 145 each have two apertures146 (FIG. 20) that are similar to the apertures 126 found in thesidewall 124 described above, with the exception that the inboardsidewall 144 also has a center aperture 146.

[0043] The box-shaped section 120 (FIG. 12A) is adjacent the box-shapedsection 119 and includes a front face wall 151, a top wall 152, a bottomwall 153, an inboard sidewall 154 and an outboard sidewall 155. Thebox-shaped section 120 is about equal in width to the box-shaped section117 (in a longitudinal direction). The inboard and outboard sidewalls154 and 155 are relatively flat (i.e. are not C-shaped). Also, the frontface wall 151 extends to a top of the box shaped section 120, and thereis not a top angled portion like the other box-shaped sections 117-119.The inboard sidewall 154 has two apertures 156 that are similar to theapertures 126 found in the sidewall 124 described above. The illustratedbox-shaped section 120 is actually divided into vertically-spaced-aparthalves, and consistent with that the front face wall 151 and also theinboard and outboard sidewalls 154 and 155 are actually divided into topand bottom halves, with the center section being entirely open exceptfor a vertical stabilizing rib 157.

[0044] The illustrated box-shaped sections 117-120 are connectedtogether by interconnecting “honeycomb-shaped” structures in the form offour horizontal ribs 160-163 (FIG. 12A) that are spaced equally apart ina vertical direction. It is contemplated that the box-shaped sections117-120 can be connected together by different arrangements and stillincorporate many of the advantages of the present energy absorber. Thetop rib 160 and the bottom rib 163 extend continuously from end to endof the energy absorber 102. The middle two ribs 161 and 162 also extendend to end of the energy absorber 102, with the exception that themiddle ribs 161 and 162 are discontinued near the centerline 115 and donot connect the two center box-shaped sections 117. Also, the ribs 161and 162 connect the top and bottom legs of the C-shaped inner portion ofwalls 125 and 134. The box-shaped sections 117-120 are also connectedtogether by a rear wall 164. The rear wall 164 completely covers a rearof the energy absorber 102, with the exception that an opening is formedin the rear wall 164 at each of the box-shaped sections 117-120 tofacilitate tooling and prevent a die lock condition. The rear wall 164not only ties the sections 117-120 together, but also forms verticalstraps that tie the top and bottom walls together to prevent the top andbottom walls from spreading apart during an impact. This also eliminatesthe need for top and bottom fasteners.

[0045] A top flange 170 (FIG. 13) and a bottom flange 171 (FIG. 14) areformed on top and bottom edges of the rear wall 164. The flanges 170 and171 wrap onto tops and bottoms of the bumper beam 101. Fingertip-likepads 172 are formed on the flanges 170 and 171 for engaging mating areason the top surface and on the bottom surface of the bumper beam 101 totemporarily frictionally retain the energy absorber 102 on the bumperbeam 101. Also, hooks 173 (FIGS. 10-11) are formed on tabs that extendfrom (and co-planar with) the top and bottom walls 122, 123, 132, 133,142, 143, 152, and 153. The hooks 173 are shaped to engage mating holesin a front face of the bumper beam 101. The hooks 173 (and also flanges53-54) provide an opportunity for “blind” snap-attachment, such as whenan operator has preassembled an energy absorber to a fascia, and thenattaches the assembled absorber/fascia as a unit to a vehicle front. Insuch event, the fascia prevents the operator from attaching the absorberto a bumper beam.

[0046] The energy absorber 102 (FIG. 11) includes integrally-formed endsections 180 and 181 that are symmetrically shaped and that areoptimally shaped to form end-located crush boxes for energy absorptionupon corner impact to a vehicle. The end sections 180 and 181 eachinclude a vertical rib 182 (FIG. 12A) that transversely crosses andconnects to the horizontal ribs 160-163 to form a honeycomb shape. Theoutboard sidewall 155 is extended rearwardly so that it substantiallycovers the open end of the tube sections on the bumper beam 101. Also,the rear wall 164 is extended at a location 164′ (FIGS. 22, 24, and 25)from the outboard sidewall 155 to form a rearwardly extending box 164″(FIG. 25) that fits adjacent an end of the bumper beam. It is noted thatthe mounting brackets 107 and 108 can include a forward loop 111 thatholds the box 164″ in place against an end of the bumper beam, ifdesired. A crescent-shaped flange 183 extends coplanar with the facefront walls 121, 131, 141, and 151. The flange 183 is stiff butflexible, such that it does a good job of supporting front-end fascia,such as RIM urethane fascia, placed on it. At the same time, the flange183 is flexible for flexing during a corner impact on a vehicle, thusreducing damage to the vehicle.

[0047] The illustrated top and bottom walls 122, 123, 132, 133, 142,143, 152, and 153 are wave-shaped or corrugated in shape to facilitatemolding and strength. The illustrated walls of the box-shaped sections117-120 and walls 160-163 and adjacent areas are about 2 mm thick, whilethe walls of the end sections 180 and 181 are about 3 to 4 mm thick.(Compare FIGS. 16-20 to the FIGS. 22-25.) However, it is contemplatedthat the walls and thickness can be made any thickness, includinglocalized variations made to optimize the energy absorption. Since themold dies are relatively non-complex (since pulls and movable componentsfor making blind surfaces are not required), the walls can be madethicker relatively easily by grinding away metal in the molding dies.Also, the apertures can be made smaller by grinding away metal, suchthat the crush/impact strength can be closely and accurately controlled,and also can be carefully adjusted and tuned to react to the actualresults of vehicle crash testing during bumper development for aparticular model vehicle. For example, by reviewing the energy absorber102 and bumper beam 101 after an impact (compare FIGS. 20 and 22 whichare before impact, and FIGS. 21 and 23 which are after impact),intelligent decisions can be made regarding what areas of the energyabsorber 102 require additional strength, and what areas need to beweakened. For example, by changing a shape of the curved edge of theapertures 126, 136, 146 and 156, a different energy absorption curveresults on a force vs deflection graph of a vehicle impact.Specifically, the rates of increase in energy absorption can becontrolled and more accurately adjusted while “tweaking” and fine-tuningthe energy absorber 102. Substitution of different material blends inthe energy absorber 102 also can help.

[0048] In particular, it is noted that the end sections 180 and 181 ofthe present energy absorber 102 form integral box-shaped sections thatprovide a very consistent and strong corner impact strength. Thehoneycomb shape formed by ribs 160-163 and ribs 153 and 182 along withthe crescent-shaped flange 183 and the interaction of the end sections180-181 with the J-shaped section 110 of the mounting bracket 107 and108 and the end of the tube sections 104 and 105 of the bumper beam 101are important aspects of the present invention. Also, an importantinventive aspect is the concept of fine-tuning the energy absorber 102by changing wall thicknesses and providing apertures of different sizesto optimize a bumper system.

[0049] Yet another important feature of the present illustrated designof the energy absorber 102 is shown by the offset 163A in lower wall163, which connects the front and rear portions 163B and 163C of wall163. During impact, the front portion 163B telescopes overlappingly ontothe rear portion 163C, with the offset 163A wrapping back upon itselfand between the portions 163B and 163C. This “wrapping” action provideshigh-energy absorption and a very consistent and predictable collapse,which is very desirable in energy absorbers.

[0050] The present invention is described as utilizing a B-shapeddouble-tube bumper beam that is rollformed and swept. The presentB-shaped bumper beam is sufficiently described herein for a personskilled in the art to understand and practice the present invention, butit is noted that the process and method of making the illustratedB-shaped bumper beam is described in greater detail in Sturrus patentU.S. Pat. No. 5,454,504, if the reader desires such information. It isspecifically contemplated that the present invention could be used incombination with a bumper beam having a shallower channel instead of thedeep channel illustrated. For example, the present invention would workon a D-shaped bumper where the bumper beam had a vertically-extendingsurface extending across a significant vertical portion of a front faceof the bumper beam but does not extend completely across a verticalfront face of the bumper beam. On the merits, the teachings of U.S. Pat.No. 5,454,504 are incorporated herein in its entirety for the purpose ofproviding a complete disclosure of the entire bumper system.

FURTHER EMBODIMENT

[0051] In regard to the illustrated preferred embodiment, a bumpersystem 320 (FIGS. 26-31) for vehicles includes a bumper beam 321 and anenergy absorber 322 attached to a face of the bumper beam 321. Theillustrated beam is rollformed and swept (see Sturrus U.S. Pat. No.5,454,504) and has a continuous B-shaped double-tubular cross section(FIG. 27). The double tubes are spaced vertically apart and include topand bottom mid-walls 323 and 324 defining a longitudinally-extendingchannel 325 along its rear surface. A polymeric energy absorber 322 hasa length with multiple box-shaped sections 327 (five box-shaped sectionsare shown, but not all are the same length) that abut the front surface326 of the bumper beam 321. The energy absorber 322 further includes aplurality of tying sections 328 that extend longitudinally between thebox-shaped sections 327 and also vertically between top and bottomportions 327 and 327″ of the box-shaped sections 327, as discussedbelow.

[0052] The B-shaped section of the bumper beam 321 (FIG. 28) includes,in addition to top and bottom mid-walls 323 and 324, a top wall 334, arear upper wall 335, a bottom wall 336, a rear lower wall 337, a primaryfront wall 338 and a channel-forming overlapping front wall 339. The toptube of the bumper beam 321 is formed by the walls 323, 334, 335, and338. The bottom tube of the bumper beam 321 is formed by the walls 324,336, 337, and 338. The top and bottom tubes are interconnected by frontwalls 338 and 339. Each of these walls 323-324 and 334-339 can be flator non-flat. For example, in some bumper systems (such as theillustrated bumper beam), it has been found to be beneficial to make thehorizontal walls 323, 324, 334, and 336 slightly bent or curved (in afront-to-rear direction), both for purposes of providing a bumper beamthat is less likely to prematurely kink and more likely to reliably andconsistently bend, but also for the purpose of ease of manufacture ofthe bumper beam. As illustrated, the mid-walls 323 and 324 include rearportions that are angled to created a tapered throat.

[0053] The energy absorber 322 is a molded component of non-foampolymer, such as a blend of PC/ABS/TPE. For example, it is contemplatedthat General Electric's XENOY polymer will work for this purpose. Theenergy absorber 322 includes five box-shaped sections 327 that abut afront of the front wall 338. Tying walls 328 hold the box-shapedsections 327 together. The illustrated box-shaped sections 327 includetop and bottom U-shaped sections 327′ and 327″. The top sections 327′engaging the top of front wall 338 are shaped slightly different (i.e.taller) than the bottom sections 327′ that engage the bottom of frontwall 338, but it is contemplated that they can be made similar in sizeand shape, if desired. The box-shaped sections 327 (FIG. 8A) eachinclude a top wall 341, a bottom wall 342, and opposing sidewalls 343and 344. A flat front wall 345 extends around walls 341-344 and forms aperimeter around them, tying the walls 341-344 together. Additionally,the box-shaped sections 327 include a top wall 341A, a bottom wall 342A,and opposing end walls 343A and 344A that extend from the outer edges offront wall 345 and extend parallel the walls 341-344, respectively. TheU-shaped top section 327 is formed by walls 341 and 342, which formparallel legs, and by wall 345, which forms a vertical leg. The U-shapedsection 327″ is formed by walls 341A and 342A, which are parallel, andby vertical leg 345A. A rear wall 346 extends outwardly from the walls341A-344A forming a perimeter. The section 328 is that part of wall 346that interconnects and ties adjacent box-like sections 327 together. Allwalls of sections 327 (and wall 328) are about 1.5 to 3.5 mm thick, ormore preferably about 2.0 mm to 2.5 mm thick. It is noted that the topand bottom walls 341, 341A, 342, 342A, when viewed from a position infront of the bumper system, can be wavy and undulating or otherwisenon-linear and non-flat in shape. The other walls can also be wavy orundulating. This provides the walls with increased strength forresisting buckling, and also helps eliminate distortions, such assnaking, that occur when molding a long part. It is also noted that thewalls 341, 341A, 342, and 342A extend longitudinally on the bumper beam321, but are discontinuous and further include non-blind surfaces toprevent die lock when molding. (i.e. This allows mold tooling to passthrough the plane of one wall to form another wall.) In other words, theenergy absorber 322 can be made by using male and female molds, neitherof which require secondary or movable die components for forming theenergy absorber 322.

[0054] The box-shaped sections 327 of the illustrated energy absorber322 are able to absorb significant energy without failure, such as maybe incurred in a low energy impact. Thus, in a low energy impact, theenergy absorber 322 absorbs the impact energy, and the bumper beam 321does not permanently or temporarily deform. In an intermediate energyimpact, the bumper beam 321 and the energy absorber 322 do deflect andabsorb energy, but do not permanently deform. However, the walls 323-324and 334-339 of the energy absorber 322 may permanently deform. In ahigh-energy impact, both the energy absorber 322 and the bumper beam 321initially absorb energy and then buckle as they approach a maximumamount of deflection. The point of buckling is designed into the bumpersystem 320 to cause a maximum amount of energy to be absorbed withoutdamaging the vehicle, while considering all relevant factors such asoccupant safety, government standards, and the like.

[0055] A top lip 353 extends rearwardly from the top of wall 346 of thebox section 327, and a bottom lip 354 extends rearwardly from the bottomof wall 346 of the box section 327. The lips 353 and 354 engage top andbottom surfaces on the bumper beam 321. Optionally, the lips 353 and 354can include attachment tabs or hooks (see hook tab 55 in FIG. 32 andhook tab 56 in FIG. 8) for engaging apertures or features in the bumperbeam 321 for retaining (temporarily or permanently) to the bumper beam321. These lips 353 and 354 are advantageous in that all (or most)fasteners can be eliminated for attaching the energy absorber 322 to thebumper beam 321. It is contemplated that the vehicle front fascia 357(FIG. 30) can be used to hold the energy absorber 322 on the bumper beam321 without any fasteners, if desired, as noted below.

[0056] It is noted that the present arrangement faces a “flat side” ofthe B-shaped cross section of the bumper beam 321 toward the energyabsorber 322, although it is contemplated that the present inventiveenergy absorber 322 can be positioned against the lobed part of theB-shaped bumper beam 321 and function satisfactorily. In such case, theB-shaped bumper beam 321 would be swept with its “flat” face on thevehicle side of the bumper beam and facing rearwardly.

[0057] In the present bumper system, the energy absorber 322 isrelatively loosely supported on the bumper beam 321. This is unusual inthat historically, automobile manufacturers want the position of theenergy absorbers closely controlled and well-fastened to the bumperbeam. However, testing has shown that a relatively loose energy absorbercan, if properly designed, actually assist in preventing prematurecollapse of the energy absorber by allowing the energy absorber toadjust to the impacting object to better “face” the impacting object asthe impact collision occurs.

[0058] It is to be understood that variations and modifications can bemade on the aforementioned structure without departing from the conceptsof the present invention, and further it is to be understood that suchconcepts are intended to be covered by the following claims unless theseclaims by their language expressly state otherwise. Further, it is to beunderstood that methods related to the above concepts are believed to bewithin a scope of the present invention.

I claim:
 1. A bumper system for a passenger vehicle comprising: a beamhaving a face and adapted for attachment to a vehicle frame; and anenergy absorber supported against the face of the beam, the energyabsorber including a longitudinally-extending top and bottom horizontalwalls, at least part of one of the top and bottom horizontal wallsincluding a front portion, a rear portion extending parallel the frontportion, and an offset mid-portion that interconnects the front and rearportions but that offsets and misaligns the front and rear portions sothat, upon a frontal impact, the front and rear portions telescopinglycollapse with the offset mid portion wrapping back upon itself with apredictable energy-absorbing collapse.
 2. The bumper system-defined inclaim 1, wherein both of the top and bottom horizontal walls include afront portion, a rear portion parallel the front portion, and an offsetmid-portion that interconnects the front and rear portions but thatoffsets and misaligns the front and rear portions so that, upon afrontal impact, the front and rear portions telescopingly collapse withthe offset mid portion wrapping back upon itself with a predictableenergy-absorbing collapse.
 3. The bumper system defined in claim 2,wherein the top and bottom horizontal walls include wavy undulations andare non-planar.
 4. The bumper system defined in claim 3, wherein thebeam includes top and bottom beam walls, and wherein the top and bottomhorizontal walls of the energy absorber generally align with the top andbottom beam walls, respectively, such that impact energy from a crash iscommunicated directly from the energy absorber to the beam.
 5. Thebumper system defined in claim 4, wherein the energy absorber includesflanges that extend overlappingly onto the top and bottom beam walls,the flanges including friction pads for frictionally engage the beam totemporarily retain the energy absorber on the beam during assembly. 6.The bumper system defined in claim 1, wherein the front face of the beamincludes apertures, and the energy absorber includes hooks that extendinto the apertures and that resiliently snap-attach to the beam fortemporarily holding the energy absorber on the beam.
 7. A bumper systemfor a passenger vehicle comprising: a beam having a face and top andbottom beam walls and being adapted for attachment to a vehicle frame;and an energy absorber supported against the face of the beam, theenergy absorber including a plurality ofhorizontally-and-longitudinally-extending top and bottom walls thatgenerally align with the top and bottom beam walls, and furtherincluding flanges that overlap onto the top and bottom beam walls andthat include at least a pair of fingertip-like friction pads thatfrictionally engage the top and bottom beam walls to temporarily retainthe energy absorber to the beam.
 8. The bumper system defined in claim7, wherein the fingertip-like friction pads engage top and bottomsurfaces of the top and bottom beam walls.
 9. The bumper system definedin claim 7, wherein the face of the beam includes apertures, and thefingertip-like friction pads of the energy absorber includes hooks thatextend into the apertures and that resiliently snap-attach to the beamfor temporarily holding the energy absorber on the beam.
 10. The bumpersystem defined in claim 7, wherein the energy absorber includes a rearwall that engages the face of the beam, and the flanges andfingertip-like friction pads extend rearwardly of the rear wall.
 11. Abumper system for a passenger vehicle comprising: a beam having frontand rear beam walls, and that is adapted for attachment to a vehicleframe; the front beam wall including at least one aperture in the frontbeam wall, with the rear beam wall including a support area locatedbehind and spaced from the at least one aperture; and an energy absorbersupported against the front beam wall, the energy absorber including aplurality of horizontally-extending longitudinally-extending top andbottom walls and further including front and rear walls, the energyabsorber walls including at least one structural column extending fromthe front wall through the rear wall and through the at least oneaperture in the front beam wall to a location near the support area onthe rear beam wall, wherein the front wall of the energy absorberreceives support from the front beam wall via the structural column. 12.The bumper system defined in claim 11, wherein the at least one apertureincludes at least two apertures, and wherein the at least one columnincludes at least two columns.
 13. The bumper system defined in claim12, wherein the at least one column defines a tubular shape.
 14. Thebumper system defined in claim 11, wherein the at least one column isconfigured to temporarily support the energy absorber on the beam. 15.The bumper system defined in claim 11, wherein the at least one columndefines a tubular shape.